| This study was conducted for the effect of surface pretreatment on bond strength of low-fusing dental porcelain to commercial pure titanium(CPT). The topography of the interface between CPT and porcelain and the structure of experimental materials were observed with SEM. The state of ionic diffusion in the interface area and the depth of the reaction layer were investigated with EPMA. Furthermore, the effect of Ti-bond system in clinical application was evaluated.Part I : Studies on the Bond Interface Between Low-fusing Dental Porcelain and CPT1. Effect of surface pretreatment on bond strength of CPT-porcelain The bond strengthes of 500℃ pre-oxidation group and 600℃ pre-oxidation group were significantly lower than those in the others groups. Failures in the test samples occurred at the oxide-metal interfaces. No remains of porcelain on the Ti surface were observed by naked eyes. However, there were less porcelain remains of 500℃ pre-oxidation group and 600℃ pre-oxidation group than the others groups. These suggested that the temperature of pre-oxidation above 500 ℃ would not be suitable for porcelain titanium restoration. The reasons possibly were : the temperature of pre-oxidation above 500 ℃ resulted in extensive diffusion of oxygen into the titanium lattice. This produced the thick and brittle alpha-Ti[o] layer which impaired the mechanical compatibility of thetitanium-ceramics joint.The results showed that there were no significantly difference among the groupsof oxidation for 5 minutes, 15 minuates,2 hours,24 hours. This suggested thatthere was affluence of time in operation. Considering the chance ofcontamination would increase, oxidation within 2 hours in the air wasrecommend.2. Observation of the topography and ionic diffusion in the interface area There were clefts and exfoliations in the 500℃ pre-oxidation group and 600℃ pre-oxidation group in SEM images, which were related to the cutting procedure of the samples production. This means the position of the fracture and brittleness of alpha-Ti[o] layer.The distribution of titanium in the interlayer in EPMA images decreased from the titanium surface to porcelain, which was opposite to the distribution of silicon.3. The depth and the elements composing of the Ti-porcelain reaction layer Twenty points (20um) acrossing the Ti-porcelain interface were quantitatively analysed. The results showed that: the mole -fraction of titanium declined from 87.92% to 0.65% and the depth of the reaction layer was nearly to 6μm. A two-layer structure composed of solid a -Ti[o] solution and an oxo-silicide, each of their depthes was nearly to 3μ m .The point borderline was at the point 16,which composed of Ti 42.31%, O 52.34%, Si 4.42%, Sn 0.93%. The ratio of Ti/O was nearly to 1/1 which suggested the phase of titanium oxide probably was TiO.The depths of solid a -Ti[o] solution and an oxo-silicide and the phases of thereaction layer play important roles in Ti-ceramics joint.3μm depth of solid a-Ti[o] solution and an oxo-silicide maybe a proper reference.Part II: Clinical Research on Ti-bond systemA total of 42 Ti-bond system restorations (fabricated for 22 patients) werefollowed for 28-30 months. The crowns were rated according to the CaliforniaDental Association system. In addition, Bleeding Index and Margin Index werealso evaluated. The majority of the patients on the three index at the baselinewere excellent.92% of the restorations on the surface and color were rated assatisfactory at the re-examination. However, the excellent dropped and theacceptable went up. This suggested that the low-fusing porcelain was with poorchemical stability.As to marginal integrity, a case was classified as unacceptable. There were threecrowns with slight marginal discrepancy, but no evidence of decay.The ceramic fracture ratio was 8% and Failure rate after 28 to 30 months was10.4%.Bleeding Index: there were no difference between crowned teeth and controlteeth. Chan...
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